/*
 * Created on 22 Jun 2006
 * Created by Paul Gardner
 * Copyright (C) Azureus Software, Inc, All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 *
 */

package com.aelitis.azureus.core.networkmanager.impl.udp;

import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.LinkedList;
import java.util.List;

import org.gudy.azureus2.core3.util.AESemaphore;

public class UDPConnection {
    private UDPConnectionSet set;
    private int id;
    private UDPTransportHelper transport;

    private List read_buffers = new LinkedList();

    private AESemaphore read_buffer_sem = new AESemaphore("UDPConnection", 64);

    private volatile boolean connected = true;

    protected UDPConnection(UDPConnectionSet _set, int _id, UDPTransportHelper _transport) {
        set = _set;
        id = _id;
        transport = _transport;
    }

    protected UDPConnection(UDPConnectionSet _set, int _id) {
        set = _set;
        id = _id;
    }

    protected UDPSelector getSelector() {
        return (set.getSelector());
    }

    protected int getID() {
        return (id);
    }

    protected void setID(int _id) {
        id = _id;
    }

    public boolean isIncoming() {
        return (transport.isIncoming());
    }

    protected void setSecret(byte[] session_secret) {
        set.setSecret(this, session_secret);
    }

    protected void setTransport(UDPTransportHelper _transport) {
        transport = _transport;
    }

    protected UDPTransportHelper getTransport() {
        return (transport);
    }

    protected void receive(ByteBuffer data)

    throws IOException {
        // packets reach us using 8K space regardless of content - trim this back for small protocol
        // messages to save memory

        int rem = data.remaining();

        if (rem < 256) {

            byte[] temp = new byte[rem];

            data.get(temp);

            data = ByteBuffer.wrap(temp);
        }

        read_buffer_sem.reserve();

        if (!connected) {

            throw (new IOException("Transport closed"));
        }

        boolean was_empty = false;

        synchronized (read_buffers) {

            was_empty = read_buffers.size() == 0;

            read_buffers.add(data);
        }

        if (was_empty) {

            transport.canRead();
        }
    }

    protected void sent() {
        // notification that a packet has been sent

        transport.canWrite();
    }

    protected boolean canRead() {
        synchronized (read_buffers) {

            return (read_buffers.size() > 0);
        }
    }

    protected boolean canWrite() {
        return (set.canWrite(this));
    }

    protected int write(ByteBuffer[] buffers, int offset, int length)

    throws IOException {
        int written = set.write(this, buffers, offset, length);

        // System.out.println( "Connection(" + getID() + ") - write -> " + written );

        return (written);
    }

    protected int read(ByteBuffer buffer)

    throws IOException {
        int total = 0;

        synchronized (read_buffers) {

            while (read_buffers.size() > 0) {

                int rem = buffer.remaining();

                if (rem == 0) {

                    break;
                }

                ByteBuffer b = (ByteBuffer) read_buffers.get(0);

                int old_limit = b.limit();

                if (b.remaining() > rem) {

                    b.limit(b.position() + rem);
                }

                buffer.put(b);

                b.limit(old_limit);

                total += rem - buffer.remaining();

                if (b.hasRemaining()) {

                    break;

                } else {

                    read_buffers.remove(0);

                    read_buffer_sem.release();
                }
            }
        }

        // System.out.println( "Connection(" + getID() + ") - read -> " +total );

        return (total);
    }

    protected void close(String reason) {
        if (transport != null) {

            transport.close(reason);

        } else {

            closeSupport(reason);
        }
    }

    protected void failed(Throwable reason) {
        if (transport != null) {

            transport.failed(reason);

        } else {

            failedSupport(reason);
        }
    }

    protected void closeSupport(String reason) {
        connected = false;

        read_buffer_sem.releaseForever();

        set.close(this, reason);
    }

    protected void failedSupport(Throwable reason) {
        connected = false;

        read_buffer_sem.releaseForever();

        set.failed(this, reason);
    }

    protected boolean isConnected() {
        return (connected);
    }

    protected void poll() {
        if (transport != null) {

            transport.poll();
        }
    }
}
